WO2010001829A1 - Feuille de nanofibres et procédé de production associé - Google Patents

Feuille de nanofibres et procédé de production associé Download PDF

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Publication number
WO2010001829A1
WO2010001829A1 PCT/JP2009/061723 JP2009061723W WO2010001829A1 WO 2010001829 A1 WO2010001829 A1 WO 2010001829A1 JP 2009061723 W JP2009061723 W JP 2009061723W WO 2010001829 A1 WO2010001829 A1 WO 2010001829A1
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WIPO (PCT)
Prior art keywords
nanofiber sheet
nanofiber
sheet
sheet according
weight
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PCT/JP2009/061723
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English (en)
Japanese (ja)
Inventor
矢野浩之
能木雅也
Original Assignee
国立大学法人京都大学
パイオニア株式会社
株式会社日立製作所
ローム株式会社
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Application filed by 国立大学法人京都大学, パイオニア株式会社, 株式会社日立製作所, ローム株式会社 filed Critical 国立大学法人京都大学
Priority to US13/001,879 priority Critical patent/US9012010B2/en
Publication of WO2010001829A1 publication Critical patent/WO2010001829A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/08—Mechanical or thermomechanical pulp
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F1/00—Mechanical deformation without removing material, e.g. in combination with laminating
    • B31F1/0003—Shaping by bending, folding, twisting, straightening, flattening or rim-rolling; Shaping by bending, folding or rim-rolling combined with joining; Apparatus therefor
    • B31F1/0035—Straightening or flattening
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H5/00—Special paper or cardboard not otherwise provided for
    • D21H5/0077—Transparent papers, e.g. paper treated with transparent-rendering compositions or glassine paper prepares from well-hydrated stock
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2301/00—Handling processes for sheets or webs
    • B65H2301/50—Auxiliary process performed during handling process
    • B65H2301/51—Modifying a characteristic of handled material
    • B65H2301/512—Changing form of handled material
    • B65H2301/5123—Compressing, i.e. diminishing thickness
    • B65H2301/51232—Compressing, i.e. diminishing thickness for flattening
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24355—Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
    • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
    • Y10T442/608—Including strand or fiber material which is of specific structural definition
    • Y10T442/614—Strand or fiber material specified as having microdimensions [i.e., microfiber]

Definitions

  • the present invention relates to a nanofiber nonwoven fabric (hereinafter referred to as “nanofiber sheet”) and a method for producing the same, and a homogeneous and flat sheet having a high elastic modulus, a low linear thermal expansion coefficient, a high light transmittance, and a cellulose only. It is related with the nanofiber sheet
  • Patent Document 1 and Patent Document 2 disclose a method of obtaining a transparent glass fiber reinforced resin by matching the refractive index of glass fiber and the refractive index of matrix resin.
  • a transparent flexible substrate used for mounting an LED or an organic electronic device is required to have low thermal expansion, high strength, high elasticity, light weight, and the like.
  • the glass fiber reinforced resin substrate can satisfy low thermal expansion and high strength, but cannot satisfy light weight.
  • the fiber diameter is micro size, it is not transparent except for a specific atmospheric temperature and a specific wavelength range, and the transparency is practically insufficient. Furthermore, flatness and surface smoothness deteriorate with respect to changes in ambient temperature.
  • Patent Document 3 shows excellent transparency, excellent surface smoothness, low thermal expansion, regardless of temperature and visible wavelength range, and without being greatly affected by the refractive index of the resin material to be combined.
  • High strength, light weight and flexible fiber reinforced composite substrate materials are described.
  • This fiber-reinforced composite material contains fibers having an average fiber diameter of 4 to 200 nm and a matrix material, and has a light transmittance of 60% or more at a wavelength of 400 to 700 nm in terms of a thickness of 50 ⁇ m.
  • Patent Document 4 describes a fiber-reinforced composite material obtained by chemically modifying the hydroxyl groups of cellulose fibers constituting the fiber-reinforced composite material in order to improve the hygroscopicity of the fiber-reinforced composite material.
  • Patent Literature 3 and Patent Literature 4 cellulose fibers produced by bacteria (hereinafter referred to as “bacterial cellulose”), or cellulose fibers obtained by fibrillating pulp or cotton to form a sheet into a matrix The material is impregnated.
  • Patent Documents 5 and 6 propose ultrafine fibers obtained by defibrating natural fibers such as cellulose fibers between two rotating disks in a suspended state.
  • the fiber is refined by repeating the mechanical defibrating process 10 to 20 times.
  • the fibers forming the sheet are sufficiently fine (nano Fiber).
  • the crystalline cellulose constituting the fiber is not broken by defibration and maintains a high degree of crystallinity. It is said.
  • Patent Document 6 a sufficiently refined nanofiber sheet is obtained by maintaining a predetermined amount of water so that the nanofiber precursor is not dried prior to defibration.
  • JP-A-9-207234 Japanese Patent Laid-Open No. 7-156279 JP 2005-60680 A JP 2007-51266 A JP 2003-155349 A JP 2008-24788 A
  • the present invention solves the above conventional problems, and is a nanofiber sheet having high transparency, high elastic modulus, low linear thermal expansion coefficient, and high flatness and smoothness, in particular, a uniform and flat sheet having high light transmittance.
  • An object of the present invention is to provide a nanofiber sheet realized only with cellulose.
  • the present inventors can suppress the surface scattering of light by smoothing the surface of the nanofiber sheet, and as a result, it is necessary to make a composite with a matrix material. It was found that a nanofiber sheet with high transparency and high elastic modulus and low linear expansion coefficient can be obtained.
  • the present invention is based on such knowledge and is summarized as follows.
  • Parallel light transmittance of light with a wavelength of 600 nm at 60 ⁇ m thickness is 70% or more
  • Young's modulus by JIS K7161 method is 10 GPa or more
  • Linear thermal expansion coefficient by ASTM D606 method is 10 ppm / K or less
  • nanofiber sheet according to any one of [1] to [4], wherein the nanofiber is obtained from wood flour.
  • the chemical modification is performed using one or more selected from the group consisting of acids, alcohols, halogenating reagents, acid anhydrides, and isocyanates.
  • Nanofiber sheet is selected from the group consisting of acids, alcohols, halogenating reagents, acid anhydrides, and isocyanates.
  • [8] A method for producing a nanofiber sheet according to any one of [1] to [7], comprising a physical surface smoothing treatment step.
  • the water content in the nanofiber precursor is 3% by weight or more in all steps before the defibration step [8] or [9]
  • the defibrating step is a step of obtaining nanofibers by defibrating a nanofiber precursor solution or dispersion having a solid content of 0.1 to 5% by weight [10] ] The manufacturing method of the nanofiber sheet of description.
  • the nanofiber sheet of the present invention achieves high transparency only with a sheet by physically smoothing the surface, etc., thereby improving the smoothness and flatness of the surface, and is combined with a matrix material. Therefore, the elastic modulus is high and the linear thermal expansion coefficient is low.
  • the nanofiber sheet As described above, in the past, in order to achieve high transparency, it was necessary to combine the nanofiber sheet and the matrix material. However, in the present invention, only the nanofiber sheet is used without using a composite material. A transparent sheet can be obtained. For this reason, a compounding process becomes unnecessary, and a sheet having a higher linear expansion coefficient and elastic modulus than that of the composite material can be obtained. Further, since the absorption of ultraviolet light by the resin is small, a sheet having a high total light transmitted light intensity at a wavelength of 300 nm or less can be obtained.
  • Total light transmittance The total light transmittance of the nanofiber sheet is obtained by irradiating light of a wavelength of 600 nm in the thickness direction on the prepared nanofiber sheet according to the method described in the section of the examples described later. Total light transmittance. Note that the total light transmittance is obtained by measuring the total transmitted light with air as a reference, the light source and the detector placed through the substrate to be measured (sample substrate) and perpendicular to the substrate. be able to. The total light transmittance of the nanofiber sheet and the composite material described in the comparative example is also measured in the same manner as described above.
  • the parallel light transmittance of the nanofiber sheet is obtained by irradiating light having a wavelength of 600 nm in the thickness direction with respect to the prepared nanofiber sheet according to the method described in the section below. It is a parallel light transmittance (linear light transmittance).
  • a parallel light transmittance linear light transmittance
  • air is used as a reference, the light source and the detector are placed through the substrate to be measured (sample substrate) and perpendicular to the substrate, and only parallel light (linearly transmitted light) is transmitted. It can be obtained by measuring the detector and the ratio measurement substrate sufficiently apart so as to detect.
  • the parallel light transmittance of the nanofiber sheet and the composite material described in the comparative example is also measured in the same manner as described above.
  • the parallel light transmittance (%) at the thickness of 60 ⁇ m is calculated from the parallel light transmittance (%) of the thickness (D ⁇ m) of the sample such as the nanofiber sheet. It can be obtained by the following proportional calculation. The same applies to the total light transmittance (%).
  • Parallel light transmittance at 60 ⁇ m thickness 100 ⁇ (Parallel light transmittance at D ⁇ m thickness / 100) (60 / D)
  • Linear thermal expansion coefficient It is a linear thermal expansion coefficient when the sample is heated from 20 ° C to 150 ° C, and is measured under the conditions specified in ASTM D696.
  • the degree of substitution representing the degree of chemical modification of the hydroxyl group of cellulose is the number of substituents introduced for the three hydroxyl groups present in the anhydroglucose unit.
  • the major axis and the major axis / minor axis ratio of wood powder are determined as follows.
  • the major axis is measured by observing the sample with a microscope.
  • the minor axis is measured, and the major axis / minor axis ratio is calculated from the result.
  • the minor axis can also be measured by passing a mesh of a predetermined size. If it is difficult to measure the size of wood flour due to aggregation, it can be dealt with by drying.
  • Moisture content Heat the sample as necessary to make it completely dry, and determine the moisture content from the difference in weight before and after.
  • wood flour is heated because it does not become absolutely dry at room temperature. Specifically, when wood powder is left in an oven at 105 ° C. overnight, it becomes completely dry, so the water content can be determined from the difference in weight before and after.
  • Quantification method of lignin It measured by the sulfuric acid method as follows.
  • the weighing bottle and the glass filter are weighed (total weight of the glass filter and the weighing bottle: Mg).
  • About 1 g of a precisely weighed sample (sample weight: Mr) is transferred to a 100 ml beaker, 15 ml of 72% sulfuric acid at about 20 ° C. is added and stirred well, and then left at 20 ° C. for 4 hours. This is washed into a 1000 ml Erlenmeyer flask using 560 ml of distilled water, and boiled for 4 hours with a reflux condenser.
  • Determination method of hemicellulose It carried out in the following procedures. About 1 g of the accurately weighed sample is put in a 200 ml beaker (sample weight: Mh), 25 ml of 17.5 wt% sodium hydroxide solution at 20 ° C. is added, the sample is uniformly moistened, left for 4 minutes, and then glass for 5 minutes. Squeeze the sample with a stick and dissociate it sufficiently to make the absorption of the alkaline solution uniform. Cover the beaker with a watch glass and leave it. The above operation is performed in a constant temperature water bath at 20 ° C. 30 minutes after adding the aqueous sodium hydroxide solution, 20 ° C. distilled water is added while stirring with a glass rod.
  • Tensile strength A sample having a thickness of 50 ⁇ m, a width of 5 mm, and a length of 50 mm is measured at a deformation rate of 5 mm / min according to the method defined in JIS K7161.
  • Nanofiber sheet The nanofiber sheet of the present invention satisfies the following physical properties i) -iii).
  • the average value in two directions preferably satisfies the following physical properties.
  • Parallel light transmittance of light having a wavelength of 600 nm at a thickness of 60 ⁇ m is 70% or more
  • Young's modulus is 10 GPa or more
  • Linear thermal expansion coefficient is 10 ppm / K or less
  • the parallel light transmittance of light having a wavelength of 600 nm at a thickness of 60 ⁇ m of the nanofiber sheet is 70% or more. If the parallel light transmittance is less than 70%, the transparency desired in the present invention cannot be obtained.
  • This parallel light transmittance is preferably 80% or more, and most preferably 90% or more. The higher the parallel light transmittance of the nanofiber sheet of the present invention, the better, but the upper limit is usually 92% or less.
  • the Young's modulus according to JIS K7161 method of the nanofiber sheet of the present invention is 10 GPa or more. If this Young's modulus is less than 10 GPa, the thermal expansion coefficient is insufficient, the elastic modulus is insufficient, and the thermal conductivity is insufficient when used as a transparent material.
  • This Young's modulus is preferably 12 GPa or more, more preferably 13 GPa or more. Although the higher Young's modulus of the nanofiber sheet of the present invention is preferable, the upper limit is usually 15 GPa or less.
  • the nanofiber sheet of the present invention has a linear thermal expansion coefficient of 10 ppm / K or less according to ASTM D606 method. When this linear thermal expansion coefficient is larger than 10 ppm / K, the target low linear thermal expansion cannot be obtained.
  • This linear thermal expansion coefficient is preferably 8 ppm / K or less, more preferably 5 ppm / K or less.
  • the nanofiber sheet of the present invention preferably has an average surface roughness (Ra) of 90 nm or less of at least one of the front surface and the back surface, in particular, at least in the usage pattern, the surface in the light incident direction.
  • This average surface roughness (Ra) is preferably 40 nm or less, more preferably 20 nm or less.
  • the average surface roughness (Ra) of the nanofiber sheet of the present invention is preferably as low as possible, the lower limit is usually 5 nm or more.
  • the maximum height difference of the surface of the nanofiber sheet of the present invention is preferably 1000 nm or less, particularly preferably 300 nm or less.
  • the nanofiber sheet may satisfy the above-mentioned average surface roughness (Ra) and further the upper limit of the maximum height difference of the surface only on one side, but at least both sides
  • the average value preferably satisfies the above-mentioned average surface roughness (Ra), and further satisfies the upper limit of the maximum height difference of the surface.
  • both surfaces of the nanofiber sheet have the above-mentioned average surface roughness (Ra).
  • the total light transmittance at a wavelength of 250 nm of the nanofiber sheet of the present invention is preferably 5% or more. If the total light transmittance is less than 5%, the high transparency intended in the present invention may not be obtained. This total light transmittance is preferably 10% or more, more preferably 20% or more. The total light transmittance of the nanofiber sheet of the present invention is preferably higher, but the upper limit is usually 50% or less.
  • the nanofiber sheet of the present invention has a tensile strength of preferably 180 MPa or more, more preferably 210 MPa or more. If the tensile strength is less than 150 MPa, sufficient strength cannot be obtained, which may affect the use of a structural material or the like to which a force is applied.
  • the upper limit of the tensile strength is usually about 400 MPa, but it is also expected to realize a high tensile strength of about 10 GPa and further about 15 GPa by an improved method such as adjusting the fiber orientation.
  • the porosity of the nanofiber sheet is preferably 10% or less, particularly preferably 5% or less.
  • Nanofiber raw material The nanofibers of the nanofiber sheet of the present invention are preferably obtained from wood flour.
  • the bacterial celluloses described in Patent Documents 3 and 4 have problems such as high cost, difficulty in obtaining a sheet that is uniform and free of waviness and warpage, and large birefringence.
  • cotton does not contain lignin and hemicellulose, so the mechanical defibrating effect is poor.
  • cotton when defibrating by a grinder treatment, cotton requires ten times more defibration processing time than wood flour. There is a problem that the crystallinity is lowered due to destruction.
  • the pulp is also dried, the mechanical defibrating efficiency is still poor.
  • the moisture content of a normal pulp is about 10 weight% at normal temperature.
  • the crystalline cellulose is destroyed by performing mechanical defibration without drying.
  • the formation of nanofibers can be achieved while maintaining a high degree of crystallinity without requiring excessive defibration treatment.
  • fibers such as bacterial cellulose, a uniform sheet without waviness or warpage can be obtained, and birefringence can be reduced.
  • Wood powder, bamboo powder or the like is preferably used as the raw material wood powder, and in particular, those having a major axis of 2 mm or less and 30 ⁇ m or more are preferred. If the major axis of the wood flour is too large, there is a possibility that defibration will be insufficient in the subsequent mechanical defibrating process. If the long diameter of the wood powder is too small, the cellulose crystals are destroyed during pulverization, the crystallinity becomes insufficient, and the intended effect may not be obtained.
  • the upper limit of the major axis of the wood flour is preferably 2 mm or less, more preferably 1 mm or less, and most preferably 500 ⁇ m or less. Further, the lower limit of the major axis of the wood flour is preferably 30 ⁇ m or more, more preferably 50 ⁇ m or more, and most preferably 100 ⁇ m or more. Further, the ratio of the major axis to the minor axis of the wood flour is not preferable because it is difficult to be applied to a grinder that is too large.
  • the major axis / minor axis is preferably 40 or less, more preferably 20 or less, and most preferably 10 or less. This ratio is usually 1 or more.
  • the nanofiber raw wood flour has a water content of 3% by weight or more. If the moisture content of the wood flour is less than 3% by weight, the cellulose fibers come close to each other, hydrogen bonds between the cellulose fibers develop, the mechanical defibrating effect is poor, and defibration becomes insufficient. If the moisture content of the wood powder exceeds 70% by weight, the wood powder is softened and difficult to handle and transport.
  • Wood powder, softwood wood powder, hardwood wood powder, etc. can be suitably used as the wood powder. However, in removing lignin, there is an advantage that hardwood wood powder can easily remove lignin. Wood powder satisfying the above-mentioned preferred physical properties can be procured from broad-leaved trees, conifers, bamboo, kenaf, palm, etc. Among them, it is preferable to procure from broad-leaved trees, coniferous trunks and branches.
  • the nanofiber sheet of the present invention preferably has a cellulose content of 90% by weight or more. When the cellulose content is less than 90% by weight, yellowing in the heating process is remarkable.
  • the cellulose content of the nanofiber sheet of the present invention is more preferably 93% by weight or more, and particularly preferably 99% by weight or more.
  • lignin content of the nanofiber sheet is large and the lignin removal process described below is not sufficiently performed, mechanical defibration will be triggered by the void after lignin removal as a trigger for mechanical defibration. The effect of increasing the efficiency cannot be obtained sufficiently.
  • a nanofiber sheet having a lignin content of more than 10% by weight is not preferable because residual lignin causes discoloration during high-temperature treatment at 180 ° C. or higher. High-temperature treatment at 180 ° C.
  • the lignin content of the nanofiber sheet is preferably 10% by weight or less.
  • lignin In order to improve the mechanical defibrating effect, lignin needs to contain a certain amount of lignin in order to exhibit a plasticizer action in the mechanical defibrating process described later. If the lignin content is less than 10 ppm, nanofiber formation by mechanical defibration tends to be insufficient, so in the present invention, the lignin content of the nanofiber sheet is preferably 10 ppm or more.
  • the lower limit of the lignin content of the nanofiber sheet is preferably 20 ppm or more, more preferably 50 ppm or more, most preferably 100 ppm or more, and the upper limit is preferably 7% by weight or less, more preferably 5% by weight or less.
  • the hemicellulose content is not particularly limited, but when the hemicellulose content is a transparent sheet, the thermal expansion coefficient is insufficiently reduced, the elastic modulus is reduced, There is a problem that the thermal conductivity coefficient decreases.
  • those with a low hemicellulose content are not as mixed as lignin, but due to the same mechanism, defibration tends to be insufficient, so the hemicellulose content is 10 wt% or less, particularly 7 wt% or less and 100 ppm or more. In particular, it is preferably 200 ppm or more.
  • ⁇ Chemical modification> In the cellulose constituting the nanofiber sheet of the present invention, a part of the hydroxyl group may be chemically modified, and by chemically modifying the hydroxyl group, heat resistance is improved, thermal decomposition temperature is improved, discoloration prevention, linear heat The expansion coefficient can be lowered and the hygroscopicity can be reduced.
  • the substituent introduced into the hydroxyl group by this chemical modification is not particularly limited, but acetyl group, propanoyl group, butanoyl group, iso-butanoyl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group, nonanoyl group, decanoyl group , Undecanoyl group, dodecanoyl group, myristoyl group, palmitoyl group, stearoyl group, pivaloyl group and the like.
  • it is acylation.
  • the nanofiber crystalline cellulose may be destroyed in the processing step for the above, so that the degree of substitution described above is 1.2 or less, more preferably 0.8 or less, particularly 0.6 or less and 0.05 or more, more preferably Is preferably 0.2 or more, particularly 0.4 or more.
  • the manufacturing method of the nanofiber sheet of the present invention is a method of manufacturing the nanofiber sheet of the present invention as described above, and includes a physical surface smoothing process.
  • the method includes a defibrating step of mechanically defibrating a nanofiber precursor such as wood flour to obtain nanofibers.
  • the step is carried out by the following procedures a) to h).
  • the water content of the nanofiber precursor is 3% by weight or more, that is, never less than 3% by weight.
  • the water content of the nanofiber precursor is preferably 4% by weight or more, more preferably 5% by weight or more.
  • a raw material wood powder is preferably used as described above.
  • seat of this invention is demonstrated according to the procedure.
  • a nanofiber sheet is produced using wood flour as a raw material, that is, a nanofiber precursor will be described as an example.
  • the method for producing a nanofiber sheet of the present invention involves physical surface smoothing. As long as the nanofiber sheet of the present invention satisfying the above-described physical properties can be produced by the chemical treatment step, materials other than wood powder can be used.
  • the degreasing step is preferably a step of performing extraction using an organic solvent, and an ethanol / benzene mixed solution is particularly preferably used as the organic solvent. That is, a methanol / toluene mixed solution is preferable because it has an advantage of high dissolution power.
  • the purpose of this step is to remove oil-soluble impurities contained in wood powder or the like by several percent or less. If the removal of oil-soluble impurities is insufficient, problems such as discoloration during high-temperature treatment, changes over time, insufficient thermal expansion reduction, and a decrease in elastic modulus may occur.
  • the lignin removal step is preferably a step of immersing wood flour in an oxidizing agent, and an aqueous sodium chlorite solution is particularly preferably used as this oxidizing agent.
  • Such a lignin removal treatment is preferable because the Wise method using sodium chlorite and acetic acid has advantages that it is easy to operate and can be applied to a large amount of wood flour.
  • For lignin removal by the Wise method 600 ml of distilled water, 4 g of sodium chlorite and 0.8 g of acetic acid are added to 10 g of raw wood flour, and heated for 1 hour with occasional stirring in a 70-80 ° C. water bath. . After 1 hour, 4 g of sodium chlorite and 0.8 g of acetic acid are added without cooling and repeated treatment. The iterative process is repeated until the wood powder turns white. For example, this operation is performed four or more times in the case of conifers and three or more times in the case of hardwoods.
  • lignin removal methods include, for example, multistage treatment by chlorination and alkali extraction employed in the pulp production process, chlorine dioxide bleaching, bleaching with oxygen in the presence of alkali.
  • chlorination because it causes a decrease in the degree of polymerization of cellulose.
  • This lignin removal treatment is preferably performed by appropriately adjusting the treatment conditions so that the nanofiber sheet having the above-mentioned lignin content can be obtained.
  • the washing step after the lignin removal treatment is performed, for example, by collecting the wood powder immersed in the sodium chlorite treatment solution by suction filtration and washing with water while sucking.
  • the amount of water used for the water washing at this time may be an amount that can neutralize the wood flour. For example, 2 L of water is used for 10 g of wood flour.
  • the hemicellulose removing step is preferably a step of immersing wood flour in an alkali, and a potassium hydroxide aqueous solution is suitably used as the alkali. If the alkali used for the removal of hemicellulose is too strong, it dissolves or alters the cellulose crystals, and if it is too weak, the effect of removing hemicellulose cannot be obtained. It is preferable to use one having a concentration of about 8% by weight. If the concentration is low, an aqueous sodium hydroxide solution can be used. However, an aqueous potassium hydroxide solution is preferably used because sodium hydroxide is easier to denature cellulose crystals than potassium hydroxide. Although the immersion time depends on the alkali concentration, for example, in the case of a 2% by weight aqueous potassium hydroxide solution, it is possible to remove hemicellulose by immersion at room temperature overnight and then heating at 80 ° C. for 2 hours.
  • the treatment conditions are appropriately adjusted so that the nanofiber sheet having the above-mentioned hemicellulose content is preferably obtained.
  • the water washing step after the hemicellulose removal step is performed, for example, by collecting the wood powder immersed in the alkali by suction filtration and washing with water while sucking.
  • the amount of water used for rinsing at this time may be an amount that can neutralize the wood flour. For example, 2 L or more of water is used for 10 g of wood flour.
  • a nanofiber precursor solution or dispersion having a solid content of 0.1 to 5% by weight.
  • the solid content is more preferably 0.1 to 3% by weight. If the solid content is too large, fluidity deteriorates before or during defibration, and defibration becomes insufficient. If the amount is too small, the defibration efficiency is poor and industrially inappropriate.
  • the mechanical defibrating is preferably performed by a grinder or a combination of a grinder and another device.
  • a grinder is a stone mill that pulverizes raw materials into ultrafine particles by impact, centrifugal force, and shearing force generated when the raw material passes through the gap between two upper and lower grinders (grinding stones). Atomization, dispersion, emulsification, and fibrillation can be performed simultaneously.
  • Other means besides the grinder include homogenizers, refiners, etc., but it is difficult to defibrate uniformly to the nano level with just the refiner or homogenizer, and usually only the grinder process or the grinder process is performed first. It is preferable to carry out refiner and homogenizer treatment thereafter.
  • facing plate-shaped grindstones are used, and preferably performed under the following conditions. Gap between grinding wheels: 1 mm or less, preferably 0.5 mm or less, more preferably 0.3 mm or less, 0.001 mm or more, preferably 0.01 mm or more, more preferably 0.05 mm or more, most preferably 0.1 or more Diameter: 10 cm or more, 100 cm or less, preferably 50 cm or less.
  • the rotational speed of the grindstone 500 rpm or more, preferably 1000 rpm or more, most preferably 1500 rpm or more, 5000 rpm or less, preferably 3000 rpm or less, most preferably 2000 rpm or less.
  • Residence time 1-30 minutes, more preferably 5-25 minutes, most preferably 10-20 minutes
  • Treatment temperature 30-90 ° C, preferably 40-80 ° C, more preferably 50-70 ° C
  • the inter-grind gap When the inter-grind gap is less than the above value, the diameter exceeds the above value, the rotational speed exceeds the above value, and the residence time exceeds the above value, the crystallinity of the cellulose decreases, and the resulting nanofiber sheet has a high elastic modulus and low heat. Since characteristics such as expansion are deteriorated, it is not preferable. If the inter-grinding gap exceeds the above value, the diameter is less than the above value, the rotational speed is less than the above value, and the residence time is less than the above value, sufficient nanofiber formation cannot be performed.
  • the defibrating temperature exceeds the above value, the wood powder will boil and the defibrating efficiency may decrease or the crystalline cellulose may deteriorate, and if it is less than the above value, the defibrating efficiency is poor.
  • the obtained water-containing nanofibers are paper-made, and the water removal is performed so that the water content is less than 3% by weight, whereby a nanofiber sheet can be obtained.
  • This water removal method is not particularly limited, but first drains water to some extent by filtration, leaving, cold press, etc., and then leaving it as it is or removing residual water completely by hot press, etc., cold press After the method, there may be mentioned a method in which the water is almost completely removed by applying to a dryer or naturally drying.
  • the filtration is a method of removing water using, for example, a vacuum filtration device.
  • the leaving as a method of removing water to some extent is a method of gradually evaporating water over time.
  • the above cold press is a method of extracting water by applying pressure without applying heat, and can squeeze out a certain amount of water.
  • the pressure in this cold press is preferably 0.01 to 10 MPa, more preferably 0.1 to 3 MPa. If the pressure is less than 0.01 MPa, the remaining amount of water tends to increase. If the pressure is more than 10 MPa, the nanofiber sheet may be broken.
  • temperature is not specifically limited, Room temperature is preferable for the convenience of operation.
  • the standing as a method of removing the remaining water almost completely is a method of drying nanofibers over time.
  • the above hot press is a method of extracting water by applying pressure while applying heat, and the remaining water can be almost completely removed.
  • the pressure in this hot press is preferably 0.01 to 10 MPa, more preferably 0.2 to 3 MPa. If the pressure is less than 0.01 MPa, water cannot be removed. If the pressure is greater than 10 MPa, the resulting nanofibers may be destroyed.
  • the temperature is preferably from 100 to 300 ° C, more preferably from 110 to 200 ° C. When the temperature is lower than 100 ° C., it takes time to remove water. On the other hand, when the temperature is higher than 300 ° C., the cellulose fibers may be decomposed.
  • the drying temperature by the dryer is preferably 100 to 300 ° C, more preferably 110 to 200 ° C. If the drying temperature is lower than 100 ° C., water may not be removed. On the other hand, if the drying temperature is higher than 300 ° C., the cellulose fibers may be decomposed. In order to obtain a nanofiber sheet with a low porosity, it is preferable to go through a pressing step, and for the purpose of further reducing the thermal expansion coefficient of the nanofiber sheet, hot pressing is more preferable. This is because the hydrogen bond at the fiber entanglement portion can be further strengthened.
  • the step of chemically modifying the cellulose hydroxyl group of the nanofiber sheet obtained by papermaking is selected from the group consisting of an acid, an alcohol, a halogenating reagent, an acid anhydride, and an isocyanate group. It is preferably a step of introducing a hydrophobic functional group by any one or more of an ether bond, an ester bond, and a urethane bond by chemical modification with a seed or two or more kinds.
  • a nanofiber sheet in which a part of hydroxyl groups of cellulose is chemically modified is referred to as a “derivatized nanofiber sheet”.
  • functional groups introduced into the hydroxyl group of cellulose by chemical modification include acetyl, methacryloyl, propanoyl, butanoyl, iso-butanoyl, pentanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, Decanoyl group, undecanoyl group, dodecanoyl group, myristoyl group, palmitoyl group, stearoyl group, pivaloyl group, 2-methacryloyloxyethylisocyanoyl group, methyl group, ethyl group, propyl group, iso-propyl group, butyl group, iso-butyl Group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dode
  • ester functional groups are particularly preferred, and acyl groups such as acetyl groups and / or methacryloyl groups are particularly preferred.
  • the chemical modification of cellulose can be performed according to a conventional method. For example, a method of immersing the nanofiber sheet described above in a solution containing a chemical modifier and holding it for a predetermined time under an appropriate condition can be employed.
  • the reaction solution containing the chemical modifier may be only the chemical modifier and the catalyst, or may be a solution of the chemical modifier.
  • Basic catalysts such as pyridine, N, N-dimethylaminopyridine, triethylamine, sodium hydride, tert-butyllithium, lithium diisopropylamide, potassium tert-butoxide, sodium methoxide, sodium ethoxide, sodium hydroxide, sodium acetate
  • a catalyst or an acidic catalyst such as acetic acid, sulfuric acid, and perchloric acid can be used.
  • a basic catalyst such as pyridine in order to increase the reaction rate and prevent the polymerization degree from decreasing.
  • Sodium acetate is preferable in that there is no problem of coloring the nanofiber sheet due to chemical modification, and the degree of substitution can be increased by raising the reaction temperature.
  • perchloric acid or sulfuric acid is preferable in that there is no problem of coloring of the nanofiber sheet due to chemical modification, and the degree of substitution can be increased at room temperature for a short time under a reaction condition of a small amount of chemical modifier addition.
  • the concentration of the chemical modifier in the reaction solution is preferably 1 to 75% by weight, and more preferably 25 to 75% by weight in the presence of a basic catalyst. Further, it is more preferably 1 to 20% by weight in the presence of an acidic catalyst.
  • the temperature condition in the chemical modification treatment is excessively high, there is a concern about the yellowing of the cellulose fiber and a decrease in the degree of polymerization, and if it is excessively low, the reaction rate decreases.
  • 10 to 40 ° C. is appropriate.
  • the contact efficiency between the nanofiber and the chemical modifying agent is increased by allowing the reaction solution to inject into the details inside the nanofiber sheet by allowing it to stand for about 1 hour under a reduced pressure of about 1 kPa. You may do it.
  • the reaction time is appropriately determined according to the reaction solution used and the reaction rate depending on the treatment conditions, but is usually about 24 to 336 hours under basic conditions and about 0.5 to 12 hours under acidic conditions. .
  • the nanofiber sheet obtained by mechanical defibration and papermaking described above has poor permeability of the reaction solution containing the above-described chemical modifier due to the crossing and close contact structure of the fibers, and the reaction rate during chemical modification is low. It may be slow.
  • the nanofiber sheet containing moisture before the moisture removal treatment is subjected to only a cold press as necessary to remove only a part of the moisture, (First step), water in the water-containing nanofiber sheet is replaced with an appropriate organic solvent (first organic solvent) (second step), and the nanofiber sheet containing the organic solvent
  • first organic solvent an appropriate organic solvent
  • the reaction solution efficiently penetrates into the hydrous nanofiber sheet (third step), and the contact efficiency between the nanofiber and the reaction solution is increased, thereby increasing the reaction rate of the chemical modification. It is preferable.
  • water and a chemical modifier are used for smooth replacement from the water in the water-containing nanofiber sheet to the first organic solvent and further to the reaction liquid containing the chemical modifier.
  • Preferred are those which are uniformly mixed with each other and have a lower boiling point than water and the reaction solution, in particular, alcohols such as methanol, ethanol, propanol and isopropanol; ketones such as acetone; tetrahydrofuran and 1,4-dioxane.
  • Water-soluble organic solvents such as ethers such as N; N-dimethylacetamide, amides such as N, N-dimethylformamide, carboxylic acids such as acetic acid, nitriles such as acetonitrile, and other aromatic heterocyclic compounds such as pyridine
  • ethers such as N
  • N-dimethylacetamide such as N
  • amides such as N, N-dimethylformamide
  • carboxylic acids such as acetic acid
  • nitriles such as acetonitrile
  • other aromatic heterocyclic compounds such as pyridine
  • ethanol, acetone and the like are preferable in terms of easy availability and handling.
  • These organic solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them.
  • the method for replacing the water in the water-containing nanofiber sheet with the first organic solvent is not particularly limited, but the water-containing nanofiber is obtained by immersing the water-containing nanofiber sheet in the first organic solvent and leaving it for a predetermined time.
  • the temperature condition for the immersion substitution is preferably about 0 to 60 ° C. in order to prevent volatilization of the first organic solvent, and is usually performed at room temperature.
  • the water-containing nanofiber sheet Prior to replacing the water in the water-containing nanofiber sheet with the first organic solvent, the water-containing nanofiber sheet is cold-pressed to remove a part of the water contained in the nanofiber sheet. And the first organic solvent are preferable for efficient replacement.
  • the degree of this press is designed so that a fiber-reinforced composite material having a desired fiber content can be obtained with a press prior to impregnation of a liquid for impregnation into a derivatized nanofiber sheet described later.
  • the thickness of the water-containing nanofiber sheet is about 1/2 to 1/20 of the thickness before pressing by pressing.
  • the pressure and holding time during the cold pressing is 0.01 to 100 MPa (however, when pressing at 10 MPa or more, the nanofiber sheet may be broken, so pressing is performed by slowing the pressing speed or the like. ), Within a range of 0.1 to 30 minutes, depending on the degree of pressing.
  • the pressing temperature is preferably about 0 to 60 ° C.
  • the water-containing nanofiber sheet whose thickness has been reduced by the press treatment is substantially maintained even when the water and the first organic solvent are replaced.
  • this press is not necessarily required, and the water-containing nanofiber sheet may be immersed in the first organic solvent as it is to replace the water with the first organic solvent.
  • the nanofiber sheet containing the organic solvent is immersed in the reaction solution described above to perform chemical modification.
  • the treatment conditions at this time are the same as the treatment conditions at the time of the chemical modification treatment of the nanofiber sheet after removing the water described above. About 118 hours and about 0.3-3 hours under acidic conditions.
  • This chemical modification is performed so that the hydroxyl group of cellulose is chemically modified with the above-described degree of substitution.
  • the physical surface smoothing method for the nanofiber sheet obtained as described above is not particularly limited, and examples thereof include polishing and pressing.
  • the above polishing is a method of removing irregularities with sandpaper or emery paper and smoothing the surface.
  • the press is a method of smoothing the surface by applying pressure with a sheet sandwiched between flat plates and rolls.
  • the sandpaper used when the surface is smoothed by polishing specifically, # 4000 to # 20000 (particle size of 3 to 0.1 ⁇ m) can be used.
  • As emery paper specifically, # 4000 to # 20000 (particle size: 3 to 0.1 ⁇ m) manufactured by Sankyo Rikagaku Co., Ltd. can be used.
  • the degree of polishing is, for example, such that the surface layer portion having a thickness of 100 to 1400 nm on the sheet surface is removed by polishing. It is preferable that it is a moderate grade.
  • the polishing can be performed only on one surface of the nanofiber sheet, but is preferably performed on both surfaces of the nanofiber sheet.
  • the degree of the applied pressure when the surface of the sheet is smoothed by pressing, it is preferable to appropriately adjust the degree of the applied pressure at that time. If the pressure is too small, the surface cannot be sufficiently smoothed, and if it is too large, the sheet may be damaged.
  • heating may be used in combination at the time of pressurization, and the heating temperature in that case is preferably 40 to 160 ° C., particularly preferably 80 to 120 ° C. If the heating temperature is too low, the smoothing effect due to heating cannot be sufficiently obtained, and if it is too high, the sheet may be thermally deteriorated.
  • This physical surface smoothing treatment step is performed by the average surface roughness (Ra) of the nanofiber sheet of the present invention, and further the maximum height difference of the surface is the above-mentioned average surface roughness (Ra) and further the maximum surface roughness. This is done so that there is a height difference.
  • the nanofiber sheet of the present invention can achieve high transparency without being combined with a matrix material, it prevents a decrease in elastic modulus and an increase in linear thermal expansion coefficient due to the combination with the matrix material. In addition, it is possible to improve the production efficiency and reduce the production cost by eliminating the compounding step.
  • the nanofiber sheet of the present invention can also be used as a composite material with a transparent resin.
  • the nanofiber sheet of the present invention due to its high transparency, high elastic modulus, high strength, heat resistance, low specific gravity, substrate materials such as wiring boards, window materials for moving bodies, base sheets for organic devices, It is particularly effective for flexible OLED sheets, surface emitting illumination sheets, thin film solar cell sheets, and the like.
  • substrate materials such as wiring boards, window materials for moving bodies, base sheets for organic devices
  • the transmitted light intensity in the ultraviolet region is high, it is effective as a substrate when a high energy wavelength is used in a solar cell.
  • It can also be applied to flexible optical waveguide substrates and LCD substrates, and is used for providing transistors, transparent electrodes, passivation films, gas barrier films, metal films, etc., inorganic materials, metal materials, precision structures on sheets, especially in roll-to-roll processes. It is effective for manufacturing applications.
  • the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.
  • the measuring method of the various physical properties of a nanofiber sheet and a fiber resin composite material is as follows.
  • Total light transmittance ⁇ Measurement device> Uses Hitachi High-Technologies' UV-4100 spectrophotometer (solid sample measurement system). ⁇ Measurement conditions> -6 mm x 6 mm light source mask used-The measurement sample was photometrically measured at the integrating sphere opening. By placing the sample at this position, both diffuse transmission light and linear transmission light reach the light receiving part inside the integrating sphere, and the total light transmittance can be measured. ⁇ No reference sample. Since there is no reference (reflection caused by the difference in refractive index between the sample and air. If there is Fresnel reflection, there is no possibility that the parallel light transmittance is 100%), there is a loss of transmittance due to Fresnel reflection. . ⁇ Light source: Iodine tungsten lamp ⁇ Measurement wavelength: 1000-190 nm
  • the lignin content and other physical properties are as described above, and the density is a value calculated from the volume and weight of the sample.
  • the minimum moisture content of the wood flour before this grinder treatment was 5% by weight.
  • the obtained water-containing nanofibers were adjusted to a suspension with a fiber content of 0.1% by weight and filtered to remove moisture, thereby forming a sheet. Further, water was completely removed by hot pressing at 55 ° C. for 72 hours at 15 kPa to obtain a dry nanofiber sheet having a thickness of 60 ⁇ m and a porosity of 3.8%.
  • Both surfaces of the obtained nanofiber sheet were polished until the average surface roughness (Ra) was 19 nm using emery paper (ultra-precision polishing film, Sankyo Rika Chemical Co., Ltd.) # 4,000- # 20,000. By this polishing, surface portions of about 1 ⁇ m on both sides of the nanofiber sheet were removed.
  • Table 2 shows measurement results of various physical properties of the obtained nanofiber sheet.
  • Example 2 In Example 1, both surfaces of the nanofiber sheet obtained by removing water were emery paper (ultra-precision polishing film, manufactured by Sankyo Rikagaku Co., Ltd.) # 4,000- # 20,000, and the average surface roughness. (Ra) A nanofiber sheet was produced in the same manner except that it was polished to 42 nm. Table 2 shows the measurement results of various physical properties of the obtained nanofiber sheet. In addition, about 1 micrometer each surface part of both surfaces of the nanofiber sheet was removed by this grinding
  • Example 1 the measurement results of various physical properties of the nanofiber sheet before surface smoothing with emery paper are shown in Table 2.
  • Example 2 In Example 1, the water-containing nanofibers obtained by the grinder treatment were adjusted to an aqueous suspension with a fiber content of 0.1% by weight, the water was removed by freeze-drying, and drying with a thickness of 120 ⁇ m and a porosity of 59% was performed. A nanofiber sheet was obtained. The measurement results of various physical properties of this product are shown in Table 2.
  • Example 3 the water-containing nanofibers obtained by the grinder treatment were adjusted to an aqueous suspension with a fiber content of 0.1% by weight and filtered to form a sheet. While filtering this sheet, alcohol such as ethanol and methanol was added from above to replace water with alcohol. Furthermore, water was completely removed by hot pressing at 55 kPa for 72 hours at 15 kPa to obtain a dry nanofiber sheet having a thickness of 90 ⁇ m and a porosity of 25%.
  • alcohol such as ethanol and methanol
  • the obtained nanofiber sheet was immersed in a photoinitiator-containing acrylic resin (TCCDDMA) under reduced pressure and allowed to stand for 12 hours. Thereafter, the nanofiber sheet impregnated with the resin was irradiated with ultraviolet rays and cured using a belt conveyor type UV irradiation device (Fusion F300 and LC6B bench top conveyor manufactured by Fusion Systems). The total irradiation energy at this time was 20 J / cm 2 . Thereafter, annealing (heat treatment) was performed in vacuum at 160 ° C. for 2 hours to obtain a fiber-reinforced composite material. The measurement results of various physical properties of this product are shown in Table 2.
  • Example 4 In Example 1, the following acetylation treatment was performed on the wood powder (refined wood powder) after the degreasing, delignification, and dehemicellulose treatments. ⁇ Acetylation treatment> 1) Purified wood powder was immersed in acetone, and water inside the wood powder was completely removed. 2) A reaction solution was prepared by adding 25 mL of acetic anhydride, 400 mL of acetic acid, 500 mL of toluene, and 2.5 mL of perchloric acid to a separable flask. 3) The purified wood flour produced in 1) was immersed in the reaction solution prepared in 2) and reacted at room temperature for 1 hour. 4) After completion of the reaction, the obtained acetylated wood flour was washed with methanol to completely remove the reaction solution inside the wood flour.
  • the obtained wood flour was adjusted to a 1% by weight aqueous suspension and subjected to a grinder treatment under the same conditions as in Example 1.
  • the minimum moisture content of the wood flour before this grinder treatment was 0% by weight.
  • the obtained water-containing nanofibers were adjusted to a suspension with a fiber content of 0.1% by weight and filtered to remove moisture, thereby forming a sheet. Furthermore, water was completely removed by hot pressing at 55 kPa for 72 hours at 15 kPa to obtain a dry nanofiber sheet having a thickness of 100 ⁇ m and a porosity of 25%.
  • the obtained nanofiber sheet was immersed in a photoinitiator-containing acrylic resin (TCCDDMA) under reduced pressure and allowed to stand for 12 hours. Thereafter, the nanofiber sheet impregnated with the resin was irradiated with ultraviolet rays and cured using a belt conveyor type UV irradiation device (Fusion F300 and LC6B bench top conveyor manufactured by Fusion Systems). The total irradiation energy at this time was 20 J / cm 2 . Thereafter, annealing (heat treatment) was performed in vacuum at 160 ° C. for 2 hours to obtain a fiber-reinforced composite material. The measurement results of various physical properties of this product are shown in Table 2.
  • Comparative Example 5 On the nanofiber sheet of Comparative Example 1, the acrylic resin used in Comparative Example 3 was applied using a spin coater (Mikasa Co., Ltd., MS-A100), the surface was smoothed, and then cured by irradiation with ultraviolet rays. I let you. The total irradiation energy at this time was 20 J / cm 2 . Furthermore, application
  • Comparative Example 6 The nanofiber sheet of Comparative Example 1 was sandwiched between two polystyrene sheets having a thickness of 40 ⁇ m, laminated, and heated and pressed at 120 ° C. for 2 minutes at 2 MPa to obtain a transparent composite material. The measurement results of various physical properties of this product are shown in Table 2.
  • the parallel light transmittance is Is good, but the total light transmittance is poor, and the linear thermal expansion coefficient and strength are also poor.
  • the nanofiber sheet of the present invention can achieve high transparency, high elastic modulus, high strength, and low linear thermal expansion without being combined with a transparent resin.

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Abstract

L’invention concerne une feuille de nanofibres présentant une transparence élevée, un module d'élasticité élevé, un faible coefficient d’expansion thermique linéaire, une planéité et un lissé élevés ou, de manière spécifique, une feuille de nanofibres permettant de disposer d’une feuille plate et uniforme à transmission lumineuse élevée et utilisant uniquement de la cellulose. Ladite feuille possède une transmittance de lumière parallèle supérieure ou égale à 70 % à une épaisseur de 60 µm, pour une lumière d’une longueur d’ondes de 600 nm. Le module de Young de cette feuille, mesuré conformément à un procédé de norme JIS K7161, est supérieur ou égal à 10 Gpa. Le coefficient d’expansion thermique linéaire de ladite feuille, mesuré conformément à un procédé de norme ASTM D606, est inférieur ou égal à 10 ppm/K.
PCT/JP2009/061723 2008-06-30 2009-06-26 Feuille de nanofibres et procédé de production associé WO2010001829A1 (fr)

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JP2008007646A (ja) * 2006-06-29 2008-01-17 Kyoto Univ 繊維樹脂複合材料
WO2008010462A1 (fr) * 2006-07-19 2008-01-24 Pioneer Corporation feuille de nanofibre, son processus de fabrication, et matériau composite renforcé de fibre

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WO2012107642A1 (fr) * 2011-02-10 2012-08-16 Upm-Kymmene Corporation Procédé pour traiter des nanofibres de cellulose
WO2012107643A3 (fr) * 2011-02-10 2012-10-26 Upm-Kymmene Corporation Procédé pour fabriquer des produits fibreux et des composites
US9469696B2 (en) 2011-02-10 2016-10-18 Upm-Kymmeme Corporation Method for processing nanofibrillar cellulose and product obtained by the method
US9534320B2 (en) 2011-02-10 2017-01-03 Upm-Kymmene Corporation Method for fabricating fiber products and composites
JP2018144291A (ja) * 2017-03-02 2018-09-20 王子ホールディングス株式会社 積層シート
JP2018144292A (ja) * 2017-03-02 2018-09-20 王子ホールディングス株式会社 積層シート
JP2020164726A (ja) * 2019-03-29 2020-10-08 王子ホールディングス株式会社 シート
JP7126982B2 (ja) 2019-03-29 2022-08-29 王子ホールディングス株式会社 シート
CN110183698A (zh) * 2019-06-28 2019-08-30 陕西科技大学 一种hec/cnc/聚多异氰酸酯复合膜及其制备方法和应用
CN110183698B (zh) * 2019-06-28 2021-11-16 陕西科技大学 一种hec/cnc/聚多异氰酸酯复合膜及其制备方法和应用

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